Selective deposition with atomic layer etch reset

ABSTRACT

Methods are provided for conducting a deposition on a semiconductor substrate by selectively depositing a material on the substrate. The substrate has a plurality of substrate materials, each with a different nucleation delay corresponding to the material deposited thereon. Specifically, the nucleation delay associated with a first substrate material on which deposition is intended is less than the nucleation delay associated with a second substrate material on which deposition is not intended according to a nucleation delay differential, which degrades as deposition proceeds. A portion of the deposited material is etched to reestablish the nucleation delay differential between the first and the second substrate materials. The material is further selectively deposited on the substrate.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. Provisional application Ser.No. 15/581,951, titled “SELECTIVE DEPOSITION WITH ATOMIC LAYER ETCHRESET,” filed Apr. 28, 2017, which claims the benefit of priority under35 U.S.C. § 119(e) to U.S. Provisional Application No. 62/487,411,titled “SELECTIVE DEPOSITION WITH ATOMIC LAYER ETCH RESET,” filed Apr.19, 2017, all of which is incorporated herein by this reference and forall purposes.

BACKGROUND

As semiconductor substrate feature sizes shrink, there is a growing needfor processing techniques to assist device shrinking and enablethree-dimensional architectures. Atomic scale processing such as atomiclayer deposition (ALD), atomic layer etch (ALE) have been found to beuseful techniques in this regard. However, challenges to continuedsemiconductor device miniaturization and defect reduction remain.

SUMMARY

Provided are methods for conducting a deposition on a semiconductorsubstrate by selectively depositing a material on the substrate. Thesubstrate has a plurality of substrate materials, each with a differentnucleation delay corresponding to the material deposited thereon.Specifically, the nucleation delay associated with a first substratematerial on which deposition is intended is less than the nucleationdelay associated with a second substrate material on which deposition isnot intended according to a nucleation delay differential, whichdegrades as deposition proceeds. A portion of the deposited material isetched to reestablish the nucleation delay differential between thefirst and the second substrate materials. The material is furtherselectively deposited on the substrate.

The etching may be performed in cycles, where a cycle includes: exposinga substrate to an etching gas to modify the surface of the substrate;and exposing the substrate to a removal gas to remove at least some ofthe modified surface. Exposing the substrate to the etching gas mayfurther include igniting a plasma. In some embodiments, the methodfurther includes applying a bias to the substrate. The etching gas maybe a chlorine-containing compound. In various embodiments, a cycleetches between about 1 Å to about 50 Å of deposited material and/orfilm. The chamber may be purged between exposures.

A deposition cycle may include: exposing the substrate to a depositionprecursor to modify the surface of the substrate; and exposing thesubstrate to a reducing agent to deposit the film. In some embodiments,the method further includes igniting a plasma. In some embodiments, atleast some of the deposition precursor adsorbs onto the surface of thesubstrate during the exposing of the substrate to the depositionprecursor. The chamber may be purged between exposures.

In some embodiments, the etching and the depositing is performed in thesame chamber. The etching may be performed nonconformally. In someembodiments, at least one of the etching or the depositing is aself-limiting reaction.

Another aspect involves a method including: (a) exposing a substratehoused in a chamber to alternating pulses of a first reactant and asecond reactant to deposit a film over the substrate, the substratehaving a first substrate material on which deposition of the film isintended and a second substrate material on which deposition of the filmis not intended, the second substrate material being different from thefirst substrate material, and the nucleation delay for the firstsubstrate material being less than the nucleation delay for the secondsubstrate material according to a nucleation delay differential, whichdegrades upon proceeding with the deposition; (b) exposing a substratehoused in a chamber to alternating pulses of an etching gas and aremoval gas to etch a portion of the deposited material to reset thenucleation delay differential between the first and second substratematerials. In some embodiments, (a) and (b) may be performed in the samechamber, without breaking vacuum. In some embodiments, (a) and (b) maybe repeated until sufficient net deposition has occurred.

The removal gas may be a carrier gas selected from the group consistingof N₂, Ar, He, and Ne. In some embodiments, (a) and (b) are performed inthe same chamber and are performed sequentially. Furthermore, thechamber may be purged between pulses. In various embodiments, (a)further includes applying a bias to the substrate. In some embodiments,the method also includes igniting a plasma when exposing the substrateto the removal gas. The method may also include igniting a plasma whenexposing the substrate to the second reactant.

In various embodiments, at least one of (a) or (b) is a self-limitingreaction. In some embodiments, (a) and (b) are repeated to depositmaterial on the substrate. In some embodiments, (a) and (b) are repeatedto etch a film on the substrate. In various embodiments, the substrateis selected from the group consisting of metals and dielectrics.

Another aspect involves an apparatus for processing substrates, theapparatus including: one or more process chambers, each process chamberhaving a chuck; one or more gas inlets into the process chambers andassociated flow-control hardware; and a controller having a processorand a memory, wherein the processor and the memory are communicativelyconnected with one another, the processor is at least operativelyconnected with the flow-control hardware, and the memory storescomputer-executable instructions for controlling the processor to atleast control the flow-control hardware by: selectively depositing amaterial on a semiconductor substrate, the substrate comprising aplurality of substrate materials having different nucleation delayscorresponding to the material deposited thereon according to anucleation delay differential; etching a portion of the materialdeposited on the substrate to reestablish the nucleation delaydifferential between the substrate materials; and further selectivelydepositing the material on the substrate.

Another aspect involves an apparatus for processing substrates, theapparatus including: one or more process chambers, each process chamberhaving a chuck; one or more gas inlets into the process chambers andassociated flow-control hardware; and a controller having a processorand a memory, wherein the processor and the memory are communicativelyconnected with one another, the processor is at least operativelyconnected with the flow-control hardware, and the memory storescomputer-executable instructions for controlling the processor to atleast control the flow-control hardware by: exposing a substrate housedin a chamber to alternating pulses of a first reactant and a secondreactant to deposit a film over the substrate, the substrate having afirst substrate material on which deposition of the film is intended anda second substrate material on which deposition of the film is notintended, the second substrate material being different from the firstsubstrate material, and the nucleation delay for the first substratematerial being less than the nucleation delay for the second substratematerial according to a nucleation delay differential, which degradesupon proceeding with the deposition; exposing a substrate housed in achamber to alternating pulses of an etching gas and a removal gas toetch a portion of the deposited material to reset the nucleation delaydifferential between the first and second substrate materials.

These and other aspects are described further below with reference tothe appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a process flow diagram depicting operations for a method inaccordance with disclosed embodiments.

FIG. 2 is another process flow diagram depicting operations for a methodin accordance with disclosed embodiments.

FIG. 3 is a schematic illustration of etch and deposition.

FIG. 4 is another process flow diagram depicting operations for a methodin accordance with disclosed embodiments.

FIG. 5 is a plot of alternating deposition and etch cycles.

FIG. 6 is a plot of nucleation delay observed on a variety of substratesurfaces.

FIG. 7 is a schematic diagram of an example process chamber forperforming disclosed embodiments.

FIG. 8 is another schematic diagram of an example process chamber forperforming disclosed embodiments.

FIG. 9 is yet another schematic diagram of an example process apparatusfor performing disclosed embodiments.

FIG. 10 is still another schematic diagram of an example processapparatus for performing disclosed embodiments.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth toprovide a thorough understanding of the presented embodiments.Embodiments disclosed herein may be practiced without some or all ofthese specific details. In other instances, well-known processoperations have not been described in detail to not unnecessarilyobscure the disclosed embodiments. Further, while the disclosedembodiments will be described in conjunction with specific embodiments,it will be understood that the specific embodiments are not intended tolimit the disclosed embodiments.

As feature sizes shrink, there is a growing need for atomic scaleprocessing such as Atomic Layer Deposition (ALD) and Atomic Layer Etch(ALE). These are cyclic processes of nominally self-limiting steps thatresult in digital and small changes in film thicknesses. The processesare characterized by relative smoothness and conformality, as well asdirectionality in certain ALE processes.

Methods provided herein relate to the combination of optimized selectivedeposition processes with controlled etching, such as ALE, to retaingrowth selectivity and improve upon defect elimination performanceduring the selective deposition process.

Selective deposition on a semiconductor substrate may be accomplished byperiodically alternating between ALD and ALE processes. Selectivedeposition enables the continued device miniaturization and fabricationof various three-dimensional (3D) architectures by building, forexample, a wafer upward from the bottom thereof. Additional advantagesfor selective deposition include, but are not otherwise limited to:simplified integration flows (i.e., without requiring separatelithography and/or etch processes), enhanced feature density and/orscaling (i.e., such that additional device features may be included in asmaller cross-sectional area) and patterning (i.e., improved overlay).

However, currently available methods for selective deposition are oftenmaterial and/or system specific, thus no generalized approach to depositmetal and/or dielectric materials selectively at will exists. Otherchallenges otherwise associated with selective deposition are thecreation of defects and the need for of a relatively narrow processwindow. Deposition selectivity may also deteriorate as depositionproceeds, since typical deposition processes are limited in theirability to assess nucleation delay and/or inability to grow materialsselectively. Further, such deterioration of deposition selectivity makesrelatively thicker film growth via selective deposition relativelydifficult.

Moreover, selective deposition may result in defects due to a lack ofprecise and/or ideal starting surface (i.e., semiconductor substrateand/or wafer), such that residual deposition materials may be formedand/or otherwise found on such undesirable surface as defects.

Disclosed methods provide selective deposition processes to obtaindifferential growth dependent upon, or otherwise by using, thenucleation delay differential observed between the respective nucleationdelays of, for example, two or more different substrate materials. Thatis, deposition processes are tailored to achieve selective depositionon, for example, a first substrate material relative to a secondsubstrate material by leveraging the fact that deposition of thematerial being deposited occurs more readily on the first substratematerial than on the second substrate material. The substrate on whichthe deposition selectively occurs has a lower or lesser nucleation delayfor the material being deposited than the substrate material on whichthe deposition selectively does not occur, such that there is adifference between the nucleation delays associated with each of the twosubstrate materials, that difference referred to as the nucleation delaydifferential. It has been found, however, that deterioration ofdeposition selectivity occurs as selective deposition proceeds. Torectify this, it has been found that highly controlled ALE processes canbe used in combination with the growth process to reset and/orreestablish the nucleation delay differential, allowing for thesubsequent expansion of an otherwise limited process window as relatedto industrial applications.

Additional benefits of combining selective deposition with controlledetching, such as ALE, include the elimination of growth defects inherentto selective deposition, such as undesirable residual metal accumulatedon a dielectric, or similar, substrate material, to be removed duringALE. Moreover, the disclosed methods assist in the generalization ofselective deposition schemes to deposit materials and/or dielectricsselectively at will by enhancing and/or otherwise optimizing nucleationdelays and/or a differential (i.e., a nucleation delay differential)observed between the nucleation delays specific to substrate materials.The disclosed methods also allow for selective deposition to occur morethan once on the same substrate.

The disclosed methods provide a controllable solution to expand theotherwise relatively narrow process window in which selective depositiontypically takes place. As discussed above, an initial selectivedeposition is conducted on a substrate composed of a plurality ofsubstrate materials, in which the deposition selectively occurs on asubstrate material having a lower or lesser nucleation delay thananother substrate material on which the deposition selectively does notoccur. In some embodiments, the nucleation delays associated withvarious substrate materials composing a substrate may be enhanced byusing optimized chemistries, i.e., as a way to effectuate surfacechemical changes, inhibition, etc., to ensure differential growth and topotentially expand the application window. Next, to enhance depositionselectivity and thereby improve throughput while decreasing defectsassociated with off-target deposition, a controllable etching process,such as ALE, is applied to the substrate to reset, restore and/orotherwise reestablish the nucleation delay and/or inhibition for aparticular substrate material upon which deposition is sought.

By reset, restore or reestablish it is meant that the nucleation delayfor the referenced material is decreased, generally substantiallydecreased, to at or near the level at the start of the selectivedeposition, for example at or within 1, 2, 5, 10, 20, 30, 40, 50, 60 70,80 or 90% of the level of nucleation delay at the start of the selectivedeposition. In some instances, the nucleation delay may be decreasedbeyond the level (less than) that at the start of the selectivedeposition. In other embodiments, the nucleation delay differential maybe enhanced by increasing the nucleation delay associated with thesubstrate material on which the deposition selectively does not occur,for example to the same or similar extent as described above withrespect to the nucleation delay decrease. In other embodiments, both adecrease and an increase in the nucleation delays associated with thematerials on which the deposition selectively does and does not occur,respectively, may be used to enhance the nucleation delay differential.

Thus, after completion of the ALE process, selectivity for deposition onvarious substrates (nucleation delay differential between varioussubstrates) is expected to increase.

The methods provided herein offer solutions for inherent defectsresultant from the selective deposition process, such as those resultantfrom residual deposition material found on, for example, undesirablenon-growth surfaces. Usage of ALE in combination with selectivedeposition allows for the removal of such residual deposition materialfrom undesirable surfaces to, for example, create better separationbetween metal and dielectric areas, as well as within various dielectricand metal sections. Thus, selective deposition schemes may thus cycle,for example, ALD and ALE steps on the same semiconductor substrate todeposit metals and/or dielectrics at will by enhancing and/or optimizingthe nucleation delay differential between different substrate materials.

FIG. 1 provides a process flow diagram for performing operations in amethod in accordance with disclosed embodiments. Operations in FIG. 1may be performed at, for example, a chamber pressure between about 1mTorr and about 100 Torr, e.g., about 1 mTorr and about 1 Torr. Themethod shown in FIG. 1 generally relates to conducting a deposition on asemiconductor substrate. Specifically, at operation 102, a semiconductorsubstrate composed of, or otherwise comprising, a plurality of distinctsubstrate materials is provided to a processing chamber.

Referring to the chamber in which the semiconductor substrate isprovided in operation 102, the chamber may be a chamber in amulti-chamber apparatus or a single-chamber apparatus. The semiconductorsubstrate may be a silicon wafer, e.g., a 200-mm wafer, a 300-mm wafer,or a 450-mm wafer, including wafers having one or more layers ofmaterial, such as dielectric, conducting, or semi-conducting materialdeposited thereon. In some embodiments, the substrate includes a blanketlayer of silicon, such as amorphous silicon, or a blanket layer ofgermanium. The substrate may include a patterned mask layer previouslydeposited and patterned on the substrate. For example, a mask layer maybe deposited and patterned on a substrate including a blanket amorphoussilicon layer.

In some embodiments, the layers on the substrate may be patterned.Substrates may have “features” such as via or contact holes, which maybe characterized by one or more of narrow and/or reentrant openings,constrictions within the feature, and high aspect ratios. The featuremay be formed in one or more of the above described layers. One exampleof a feature is a hole or via in a semiconductor substrate or a layer onthe substrate. Another example is a trench in a substrate or layer. Invarious embodiments, the feature may have an under-layer, such as abarrier layer or adhesion layer. Non-limiting examples of under-layersinclude dielectric layers and conducting layers, e.g., silicon oxides,silicon nitrides, silicon carbides, metal oxides, metal nitrides, metalcarbides, and metal layers.

In some embodiments, the features may have aspect ratios of at leastabout 2:1, at least about 4:1, at least about 6:1, at least about 10:1,at least about 30:1, or higher. Protection of feature sidewalls may bedesirable at high aspect ratios. Disclosed methods may be performed onsubstrates with features having an opening less than about 150 nm. Afeature via or trench may be referred to as an unfilled feature or afeature. A feature that may have a reentrant profile that narrows fromthe bottom, closed end, or interior of the feature to the featureopening. In some embodiments, the methods described herein may be usedto form features having these characteristics.

Next, at operation 104, a material is selectively deposited, for exampleas described with reference to FIG. 3 below, on one or more substratematerials of the semiconductor substrate, where the substrate materialshave different nucleation delays corresponding to the material depositedthereon according to a nucleation delay differential. For example,deposition by, for example, ALD, of aluminum nitride (AlN) on a metal,such as tungsten (W) substrate may result in a different nucleationdelay observed than the deposition of AlN on, for example a dielectricsubstrate such as SiO₂. This nucleation delay differential can be usedto achieve selective deposition on the material with the lessernucleation delay relative to the material with the greater nucleationdelay.

Generally, ALD is a technique that deposits thin layers of materialusing sequential self-limiting reactions. ALD may be performed using anysuitable technique. In various embodiments, ALD may be performed withplasma, or may be performed thermally. Also, operation 104 may beperformed in cycles, i.e. referred to herein as an “ALD cycle.”

The concept of an ALD cycle is relevant to the discussion of variousembodiments herein. An ALD cycle, typically, is the minimum set ofoperations used to perform a surface deposition reaction one time. Forexample, the result of one successful ALD cycle is the production of atleast a partial silicon-containing film layer on a desired substratesurface, such as the first substrate material of operation 104.Typically, an ALD cycle includes operations to deliver and adsorb atleast one reactant to the substrate surface, to then react the adsorbedreactant with one or more reactants residing on the substrate surface toform, for example, at least a partial layer of film. The ALD cycle mayinclude certain ancillary operations such as sweeping one of thereactants or byproducts and/or treating the partial film as deposited.Generally, a cycle contains one instance of a unique sequence ofoperations. As an example, an ALD cycle may include the followingoperations: (i) delivery/adsorption of a silicon-containing precursor,(ii) purging of silicon-containing precursor from the chamber, (iii)delivery of a second reactant and a plasma, and (iv) purging of plasmafrom the chamber.

In some embodiments, aluminum nitride (AlN) may be deposited on varioussubstrates of interest via an ALD operation and/or cycle, suchsubstrates including (but not limited to), the following: silicon oxide(SiO₂), silicon nitride (Si₃N₄), silicon carbide (SiC), aluminum oxide(Al₂O₃), and aluminum nitride (AlN). Also, AlN may be deposited ongeneric high-κ dieletric layers such as hafnium (Hf), zirconium (Zr) andtin oxide (SnO₂) and/or conducting films such as tungsten (W), copper(Cu), cobalt (Co), aluminum (Al), titanium (Ti), silicon (Si) and carbon(C) individually and/or in any combination.

FIG. 3 shows an example schematic illustration of an ALD cycle fordepositing silicon oxide (SiO₂). Diagrams 304 a-304 e show a generic ALDcycle. In 304 a, a silicon substrate is provided, which includes manysilicon atoms. In 304 b, oxygen is introduced to the substrate as oxygenradicals, which modify the surface of the substrate. This may be thedelivery of the reactant and plasma. Note some oxygen radicals areadsorbed onto the surface of the substrate as an example. In 304 c, theoxygen radicals are purged from the chamber. In 304 d, asilicon-containing precursor or silicon source is introduced and thesilicon source reacts with the oxygen radicals adsorbed on the surfaceof the substrate. In 304 e, the chamber is purged and the byproducts areremoved, leaving behind a deposited layer of SiO₂.

Alternative to the selection of SiO₂ as a deposition material, in someembodiments, a metal such as aluminum (Al) and/or copper (Cu) isdeposited via ALD on, for example, a first substrate surface on whichdeposition is intended during operation 104. In some embodiments, thefirst substrate surface may be comprised of substantially aluminumnitride (AlN). Moreover, trimethylaluminum (Al₂(CH₃)₆) may provide asuitable precursor to supply Al needed as a deposition material to, forexample, deposit on a substrate substantially comprising AlN, where asubsequent nucleation delay is observed. Specifically, Al₂(CH₃)₆ may bedeposited in a relatively controlled manner from, for example, 250° C.to 350° C., above which decomposition is observed.

In some embodiments, the films deposited by ALD may be highly conformal.Conformality of films may be measured by the step coverage. Stepcoverage may be calculated by comparing the average thickness of adeposited film on a bottom, sidewall, or top of a feature to the averagethickness of a deposited film on a bottom, sidewall, or top of afeature. For example, step coverage may be calculated by dividing theaverage thickness of the deposited film on the sidewall by the averagethickness of the deposited film at the top of the feature andmultiplying it by 100 to obtain a percentage.

Unlike a chemical vapor deposition (CVD) technique, ALD processes usesurface-mediated deposition reactions to deposit films on alayer-by-layer basis. In one example of an ALD process, a substratesurface, including a population of surface active sites, is exposed to agas phase distribution of a first precursor, such as asilicon-containing precursor, in a dose provided to a process chamberhousing the substrate. Molecules of this first precursor are adsorbedonto the substrate surface, including chemisorbed species and/orphysisorbed molecules of the first precursor. It should be understoodthat when the compound is adsorbed onto the substrate surface asdescribed herein, the adsorbed layer may include the compound as well asderivatives of the compound. For example, an adsorbed layer of asilicon-containing precursor may include the silicon-containingprecursor as well as derivatives of the silicon-containing precursor. Incertain embodiments, an ALD precursor dose partially saturates thesubstrate surface. In some embodiments, the dose phase of an ALD cycleconcludes before precursor contacts the substrate to evenly saturate thesurface. Typically, the precursor flow is turned off or diverted at thispoint, and only purge gas flows. By operating in this sub-saturationregime, the ALD process reduces the cycle time and increases throughput.However, because precursor adsorption is not saturation limited, theadsorbed precursor concentration may vary slightly across the substratesurface. Examples of ALD processes operating in the sub-saturationregime are provided in U.S. patent application Ser. No. 14/061,587,filed Oct. 23, 2013, titled “SUB-SATURATED ATOMIC LAYER DEPOSITION ANDCONFORMAL FILM DEPOSITION,” which is incorporated herein by reference inits entirety. After a first precursor dose, the reactor is thenevacuated to remove any first precursor remaining in gas phase so thatonly the adsorbed species remain. A second reactant, such as an oxygenor nitrogen-containing gas, is introduced to the reactor so that some ofthese molecules react with the first precursor adsorbed on the surface.In some processes, the second precursor reacts immediately with theadsorbed first precursor. In other embodiments, the second precursorreacts only after a source of activation is applied temporally. Thereactor may then be evacuated again to remove unbound second precursormolecules. Additional ALD cycles may be used to build film thickness.

In some implementations, the ALD methods include plasma activation, suchas when the second reactant is delivered to a chamber. As describedherein, the ALD method and apparatuses described herein may be conformalfilm deposition (CFD) methods, which are described generally in U.S.patent application Ser. No. 13/084,399 (now U.S. Pat. No. 8,728,956),filed Apr. 11, 2011, and titled “PLASMA ACTIVATED CONFORMAL FILMDEPOSITION,” and in U.S. patent application Ser. No. 13/084,305, filedApr. 11, 2011, and titled “SILICON NITRIDE FILMS AND METHODS,” which areherein incorporated by reference in its entireties. Additional examplesof ALD processes are described in Puurunen, “Surface chemistry of atomiclayer deposition: for the trimethylaluminum/water process”, 97 J.Applied Physics 12301 (2005), which is herein incorporated by referencefor the purpose of providing description for suitable ALD processes.

Specifically, in some embodiments, in operation 104, a thin film and/ormaterial is deposited on a first semiconductor substrate material onwhich deposition is sought by, for example, ALD. In various embodiments,a silicon-containing material and/or film is deposited in operation 104.Example silicon-containing films include silicon oxide, siliconoxynitride and silicon nitride. In some embodiments, a metal ormetal-containing film may be deposited. Moreover, in some embodiments,operation 104 may be performed prior to operation 106 to cycle throughoperations 102-108 as needed. Alternatively, in some embodiments,operation 106 may be performed prior to operation 104.

Further, in operation 104, in some embodiments, a carrier gas, such asN₂, Ar, Ne, He, and combinations thereof, may be continuously flowed.The carrier gas may be used as a purge gas. The inert gas may beprovided to assist with pressure and/or temperature control of theprocess chamber, evaporation of a liquid reactant, more rapid deliveryof the reactant and/or as a sweep gas for removing process gases fromthe process chamber and/or process chamber plumbing.

Provided herein is an example of adsorption and second reactant deliveryoperations that may be performed in operation 104. In an adsorptionoperation of an ALD cycle, a substrate on which ALD is intended may beexposed to a film precursor, such as silicon tetrachloride (SiCl₄), toadsorb onto the substrate surface. In some embodiments, the filmprecursor may be a silicon-containing precursor. In some embodiments,the film precursor, such as SiCl₄, may be adsorbed onto about 60% of thesubstrate surface. In various embodiments, when the film precursor isflowed to the chamber, the film precursor adsorbs onto active sites onthe surface of the substrate, forming a thin layer of the film precursoron the surface. In various embodiments, this layer may be less than amonolayer.

After adsorption, the chamber may be optionally purged to remove excessprecursor in gas phase that did not adsorb onto the surface of thesubstrate. Purging may involve a sweep gas, which may be a carrier gasused in other operations or a different gas. In some embodiments,purging may involve evacuating the chamber.

In a second reactant delivery operation of an ALD cycle, the substratemay be exposed to a second reactant and, optionally, a plasma. Invarious embodiments, the second reactant is oxygen (O₂) or nitrogen (N₂)or combinations thereof. In some embodiments where a silicon oxide layeris deposited, oxygen is used as the second reactant. In someembodiments, second reactant flow and the plasma are both turned on. Insome embodiments, second reactant flow may be turned on prior to turningon the plasma to, for example, allow the second reactant flow tostabilize.

In some embodiments, the optional plasma is an in-situ plasma, such thatthe plasma is formed directly above the substrate surface in thechamber. In various embodiments, the plasma may be an inductivelycoupled plasma or a capacitively coupled plasma. A inductively coupledplasma may be set at a plasma between about 50 W and about 2000 W. Insome embodiments, a bias may be applied between about 0V and about 500V.During delivery of the second reactant, the film precursor, such asSiCl₄, is turned off. The substrate may be exposed to the secondreactant and the optional plasma for a duration that exceeds a time forplasma to interact with all precursors adsorbed on the substratesurface, forming a continuous film atop the substrate surface.

After the second reactant delivery operation, the chamber may be purged,such as by introducing a carrier or inert gas. Conditions for thisoperation may be any of those described above for purge processes.

In various embodiments, ALD cycles may be repeated. For example,operations for ALD may be performed for about 5 to about 70 cycles, evenup to 300 cycles prior to substantial growth of the deposited filmand/or layer of material. Thus, any suitable number of deposition cyclesmay be included and/or performed to deposit a desired film thickness ofthe deposited film. In some embodiments, an ALD cycle may deposit about1 Å per cycle. Depending on the exposure time of the operations, eachcycle may deposit a film, such as a silicon oxide or silicon oxynitridefilm, having a thickness between about 0.05 Å and about 5 Å. In someembodiments, about two to about three cycles of ALD may be performed perminute. In some embodiments, more than about three cycles may beperformed per minute, such as in chambers with inlets positioned to becloser to the substrate.

In some embodiments, ALD operations produce conformal films capable ofprotecting the features from lateral etching in subsequent ALEprocesses, which may occur in the same chamber. In some embodiments, ALDis integrated to selectively deposit films on a substrate, such as todeposit films on corners of a feature to protect them from erosionduring etching processes. In some embodiments, at least one of operation104 and 106 is self-limiting reaction. In some embodiments, at least oneof operation 104 and 106 is as self-limiting reaction as possible. Forexample, in some embodiments, only operation 106 is a self-limitingprocess. In some embodiments, only operation 104 is a self-limitingprocess. In some embodiments, both operations 104 and 106 areself-limiting. In various embodiments, operations 104 and 106 may beperformed sequentially. Examples of sequentially performing theseoperations are further described below with respect to FIG. 3.

A nucleation delay, as further illustrated in FIG. 6, is observed atoperation 104 as associated with the first substrate material.Specifically, as shown in FIG. 6, various substances, such as aluminumnitride (AlN) are deposited on a semiconductor substrate, which may becomprised substantially of metal, such as tungsten (W) or copper (Cu),silicon oxide (SiO₂), a dielectric such as hafnium (Hf), zirconium (Zr),or tin oxide (SnO₂). In some embodiments, as observed and shown in FIG.6, deposition of aluminum (Al) from a trimethylaluminum (Al₂(CH₃)₆)precursor on any one or more of the above substrate materials may resultin film mass growth.

As shown in FIG. 6, the nucleation delay observed between the twometals, i.e. W and Cu, is substantially less than between the metals anda dielectric, such as either W or Cu and SiO₂, for example. Further,observations of ALD in operation 104 may indicate that a metal substratesurface will generally catalyze the decomposition of a precursor fasterthan a dielectric surface.

Moreover, careful exposure and/or handling of the deposition material ina deposition chamber, i.e. to the material and/or substance to bedeposited, such as aluminum (Al) derived from a trimethylaluminum(Al₂(CH₃)₆) precursor, may allow for the successful deposition of thematerial prior to its decomposition on, for example, a dielectricsurface upon which deposition is sought. Nevertheless, in someembodiments, opposite nucleation behavior may be observed on a W or Cusurface that is fully reduced and/or at low temperatures. Also,Al₂(CH₃)₆ may be observed to tend to react in a predictable manner, or“cleanly,” with hydroxyl-rich surfaces. Further, in some embodiments,desirable nucleation delays may be obtained via known methods, thusfurther discussion of such methods is omitted.

Further, in some embodiments, deposition may be selectively avoided, atoperation 104, on a second substrate material of the semiconductorsubstrate on which deposition is not intended, i.e. in the same chamberas where deposition occurs on the first substrate material assubstantially described earlier.

Following operation 104, a portion of the material deposited on thesubstrate is etched to reestablish the nucleation delay differentialbetween the different substrate materials at operation 106.Specifically, in operation 106, the substrate is etched by ALE in thechamber. ALE is a technique that removes thin layers of material usingsequential self-limiting reactions. Generally, ALE may be performedusing any suitable technique. Examples of atomic layer etch techniquesare described in U.S. Pat. No. 8,883,028, issued on Nov. 11, 2014; andU.S. Pat. No. 8,808,561, issued on Aug. 19, 2014, which are hereinincorporated by reference for purposes of describing example atomiclayer etch and etching techniques. In various embodiments, ALE may beperformed with plasma, or may be performed thermally.

Operation 106, as shown in FIG. 1, may be performed in cycles. Theconcept of an “ALE cycle” is relevant to the discussion of variousembodiments herein. Generally an ALE cycle is the minimum set ofoperations used to perform an etch process one time, such as etching amonolayer. The result of one cycle is that at least some of a film layeron a substrate surface is etched. Typically, an ALE cycle includes amodification operation to form a reactive layer, followed by a removaloperation to remove or etch only this modified layer. The cycle mayinclude certain ancillary operations such as sweeping one of thereactants or byproducts. Generally, a cycle contains one instance of aunique sequence of operations. As an example, an ALE cycle may includethe following operations: (i) delivery of a reactant gas, (ii) purgingof the reactant gas from the chamber, (iii) delivery of a removal gasand optional plasma, and (iv) purging of the chamber. In someembodiments, etching may be performed nonconformally.

After completion of etching as necessary at operation 106, material isfurther selectively deposited on the semiconductor substrate atoperation 108, where such selective deposition typically benefits fromenhanced deposition selectivity resultant from the successful completionof operations 104 and 106, etc.

In some embodiments, operations 102 and 104 may be optionally repeatedas necessary, as may be operations 106 and 108. Further, operation 104may be completed by ALD, while operation 106 may be completed by ALE,for example. Also, operations 102-108 may be repeated indefinitely untila desirable semiconductor feature profile is attained.

Further, in some embodiments, the nucleation delay associated with afirst substrate material on which deposition is intended is less than anucleation delay associated with a second substrate material on whichdeposition is not intended. And, in some embodiments, the nucleationdelay differential degrades as deposition proceeds, i.e. upon completionof operation 104.

Referring now to FIG. 2, a process flow diagram for another embodimentof performing operations in a method as disclosed herein is shown. Insome embodiments, the process flow illustrated by FIG. 2 may occur insubstantially the same manner as the process flow shown by FIG. 1, thusa redundant description of the same is omitted.

Referring to operations 206 a and/or 206 b in FIG. 2, a nucleation delayND₁, as further illustrated in FIG. 6, is observed at operation 206 a asassociated with the first substrate material.

Specifically, and as shown in FIG. 6, the nucleation delay observedbetween the two metals, i.e. W and Cu, is substantially less thanbetween the metals and a dielectric, such as either W or Cu and SiO₂,for example. Further, observations of ALD in operation 204 a, asconducted in operation 206 a, may indicate that a metal substratesurface will generally catalyze the decomposition of a precursor fasterthan a dielectric surface.

Returning to FIG. 2, deposition may be selectively avoided, at operation204 b, on a second substrate material of the semiconductor substrate onwhich deposition is not intended, i.e. in the same chamber as wheredeposition occurs on the first substrate material as substantiallydescribed earlier. Accordingly, a nucleation delay ND₂ may be observedat operation 206 b. In some embodiments, the nucleation delay ND₁associated with ALD on the first substrate material may be lesser thanthe nucleation delay ND₂ associated with the second substrate materialsuch that a nucleation delay differential, ΔND, may be calculatedbetween ND₂ and ND₁ as shown in operation 208. Further, in someembodiments, ΔND may approach zero (0) as ALD proceeds as shown in, forexample, operation 204 a.

Following the calculation of the nucleation delay differential, ΔND, inoperation 208, a portion of the material deposited on the firstsubstrate material at operation 204 a and/or a portion of the materialdeposited on the second substrate material at operation 204 b is etchedby, for example ALE, to reset and/or otherwise reestablish ΔND.

In operation 210, the substrate is etched by, for example, theperformance of one or more cycles of ALE in the chamber. FIG. 3 showstwo example schematic illustrations of an ALE cycle, such as may be usedto implement the processes illustrated in FIGS. 1 and 2. Diagrams 300a-300 e show a generic ALE cycle. In 300 a, the substrate is provided.In 300 b, the surface of the substrate is modified. In 300 c, the nextstep is prepared. In 300 d, the modified layer is being etched. In 300e, the modified layer is removed. Similarly, diagrams 302 a-302 e showan example of an ALE cycle for etching a silicon film. In 302 a, asilicon substrate is provided, which includes many silicon atoms. In 302b, reactant gas chlorine is introduced to the substrate which modifiesthe surface of the substrate. The schematic in 302 b shows that somechlorine is adsorbed onto the surface of the substrate as an example.Although chlorine is depicted in FIG. 3, any chlorine-containingcompound or suitable reactant may be used. In 302 c, the reactant gaschlorine is purged from the chamber. In 302 d, a removal gas argon isintroduced with a directional plasma as indicated by the Ar⁺ plasmaspecies and arrows, and ion bombardment is performed to remove themodified surface of the substrate. During this operation, a bias isapplied to the substrate to attract ions toward it. In 302 e, thechamber is purged and the byproducts are removed.

A cycle may only partially etch about 0.1 nm to about 50 nm of material,or between about 0.1 nm and about 5 nm of material, or between about 0.2nm and about 50 nm of material, or between about 0.2 nm and about 5 nmof material. The amount of material etched in a cycle may depend on thepurpose of integrating with ALD. For example, if ALD is integrated toprotect the sidewalls, then the amount etched in ALE cycles may bevaried such that performing ALD protects the exposed sidewalls at thebottom of the feature. In some embodiments, a cycle of ALE may removeless than a monolayer of material.

Etching chemistry is introduced into the chamber in operation 210 ofFIG. 2. As described herein, in operations where materials areintroduced into the chamber, in some embodiments involving atomic layeretch using a plasma, the reactor or chamber may be stabilized byintroducing the chemistry into the chamber prior to processing thesubstrate or wafer. Stabilizing the chamber may use the same flow rates,pressure, temperatures, and other conditions as the chemistry to be usedin the operation following the stabilization. In some embodiments,stabilizing the chamber may involve different parameters. In someembodiments, a carrier gas, such as N₂, Ar, Ne, He, and combinationsthereof, is continuously flowed during operation 210. In someembodiments, a carrier gas is only used during removal. The carrier gasmay be used as a purge gas in some operations as described below. Insome embodiments, another reactant gas, such as oxygen, is used duringoperation 210 to remove a modified layer. In some embodiments, a carriergas is not flowed during removal.

Provided herein is an example of modification and removal operationsthat may be performed in operations 106, shown in FIG. 1, and 210 shownin FIG. 2. The modification operation forms a thin, reactive surfacelayer with a thickness that is more easily removed than the un-modifiedmaterial in the subsequent removal operation. In a modificationoperation, a substrate may be chlorinated by introducing chlorine intothe chamber. Chlorine is used as an example etchant species in disclosedembodiments, but it will be understood that in some embodiments, adifferent etching gas is introduced into the chamber. The etching gasmay be selected depending on the type and chemistry of the substrate tobe etched. In some embodiments, a plasma may be ignited and chlorinereacts with the substrate for the etching process. In some embodiments,chlorine may react with the substrate or may be adsorbed onto thesurface of the substrate. In various embodiments, chlorine is introducedinto the chamber in a gaseous form and may be optionally accompanied bya carrier gas which may be any of those described above. The speciesgenerated from a chlorine plasma can be generated directly by forming aplasma in the process chamber housing the substrate or they can begenerated remotely in a process chamber that does not house thesubstrate, and can be supplied into the process chamber housing thesubstrate. In some embodiments, a plasma is not used and chlorine may beintroduced thermally into the chamber.

In various embodiments, the plasma may be an inductively coupled plasmaor a capacitively coupled plasma. An inductively coupled plasma may beset at a plasma between about 50 W and about 2000 W. In someembodiments, a bias may be applied between about 0V and about 500V.

In some embodiments, a purge may be performed after a modificationoperation. In a purge operation, non-surface-bound active chlorinespecies may be removed from the process chamber. This can be done bypurging and/or evacuating the process chamber to remove the activespecies, without removing the adsorbed layer. The species generated inchlorine plasma can be removed by simply stopping the plasma andallowing the remaining species decay, optionally combined with purgingand/or evacuation of the chamber. Purging can be done using any inertgas such as N₂, Ar, Ne, He and their combinations.

In a removal operation, the substrate may be exposed to an energy source(e.g. activating or sputtering gas or chemically reactive species thatinduces removal), such as argon or helium, to etch the substrate bydirectional sputtering. In some embodiments, the removal operation maybe performed by ion bombardment. During removal, a bias may beoptionally turned on to facilitate directional sputtering. In someembodiments, ALE may be isotropic.

The amount of sputtering gas may be controlled such as to etch only atargeted amount of material. In various embodiments, the pressure of thechamber may vary between the modification and removal operations. Thepressure of the gas may depend on the size of the chamber, the flow rateof the gas, the temperature of the reactor, the type of substrate, andthe size of substrate to be etched. If the bias is turned on duringremoval, the bias may be set at about 50 eV for etching features,trenches, or holes in a soft material such as amorphous silicon. In someembodiments, the chamber may be purged after a removal operation. Purgeprocesses may be any of those used for a purge after a modificationoperation.

In various embodiments, the modification and removal operations may berepeated in cycles, such as about 1 to about 30 cycles, or about 1 toabout 20 cycles. Any suitable number of ALE cycles may be included toetch a desired amount of film. In some embodiments, ALE is performed incycles to etch about 1 Å to about 50 Å of the surface of the layers onthe substrate. In some embodiments, cycles of ALE etch between about 2 Åand about 50 Å of the surface of the layers on the substrate.

In some embodiments, the described ALD and ALE processes discussedherein may be performed in different chambers, with the substrate beingtransferred between the chambers without breaking vacuum. In otherembodiments, the described ALD and ALE processes may be performed in thesame chamber, with no vacuum break between deposition and etchoperations.

Returning to FIG. 2, a bias is optionally applied at an operation 212.Applying a bias may etch sidewalls, so in various embodiments, a biasmay not be applied continuously and may be applied after various cyclesof ALD and ALE. This operation may be performed to break through thefilm deposited by ALD. In some embodiments, the bias is set to about 80eV to break through the layer deposited by cycles of ALD.

Operation 214 determines whether sufficient reset and/or reestablishmentof ΔND has been performed. If ΔND is not sufficiently reset, operations204 a and/or 204 b-214 may be repeated. Further, in some embodimentsoperations 204 a and/or 204 b-214 are performed in the same chamber orwithout breaking vacuum for the repeated cycles as in the initial cycle.

FIG. 4 provides further illustration of processes for implementingdisclosed embodiments, combining ALE and selective ALD operations in asingle process flow. In operation 400, a substrate housed in a chambermay be exposed to an etchant or etching gas to modify the surface of thesubstrate. This may be referred to as a “surface modification”operation. During this operation, a carrier gas may be optionallyflowed, while an etchant is flowed to the chamber. A carrier gas may beany of the carrier gases described above with respect to FIGS. 1-3. Insome embodiments, a carrier gas is not flowed during surfacemodification. The etchant may be flowed such that it modifies only thetop surface of the substrate. In various embodiments, a bias may beapplied during operation 400. The bias may be applied at a power betweenabout 0V and about 500V.

Returning to FIG. 4, in operation 402, the modified layer of thesubstrate may be removed from the substrate by exposing the substrate toa sputtering gas in a removal operation, which may be the same as ordifferent from a carrier gas. In various embodiments, at least part ofthe substrate surface may be etched in this operation. The exampleprovided above with respect to operation 210, shown in FIG. 2, may beused in accordance with these operations. Performing operations 400 and402 may, in some embodiments, constitute performing ALE once. In someembodiments, operations 400 and 402 may be optionally repeated one ormore times (e.g., in one or more cycles).

Operation 402 may correspond to a removal phase. In some embodiments, acycle may include more operations. During removal, a carrier gas may beflowed without flowing any other chemistry. The carrier gas may beflowed to help facilitate purging of the modified layer as it is etched.

In operation 404, the substrate is exposed to a first reactant to adsorbthe first reactant onto at least some of the substrate surface. Thisoperation may be performed without breaking vacuum from performingoperations 400 and 402. In some embodiments, the first reactant is afilm precursor as described herein. In various embodiments, the firstreactant may adsorb onto active sites of the substrate. The abovedescribed examples of adsorption during an ALD cycle are relevant tothis operation.

Operation 404 may correspond to first precursor exposure phase. Duringthis operation, the first precursor may be flowed with an optionalcarrier gas. Note that during this operation, the etchant flow andsecond reactant flow to be described further below may not be flowed.This operation may be performed for a duration sufficient to saturate atleast part of the surface of the substrate. In some embodiments, atleast about 40%, or at least about 60%, or at least about 80%, or about100% of the surface may be saturated.

In some embodiments, after performing the first precursor exposurephase, the chamber housing the substrate may be optionally purged in apurge phase. During the purge phase, a carrier gas is flowed to removeexcess first precursor that did not adsorb onto the surface of thesubstrate. In some embodiments, the purge phase is not performed.

Returning to FIG. 4, operation 406 may be performed such that thesubstrate is exposed to a second reactant. In various embodiments, thesecond reactant may be a reducing agent. The second reactant reacts withthe adsorbed layer to deposit a thin film on the substrate. Note that insome embodiments, operations 404 and 406 may be performed in reversesuch that operation 406 is performed prior to adsorbing the firstreactant onto the surface of the substrate.

Operation 406 may correspond to second reactant exposure phase. Duringthis phase, the second reactant is flowed, and a carrier gas isoptionally flowed. In some embodiments, a second reactant is flowedwithout a carrier gas. The etchant and first precursor flow are notturned on during this phase. In various embodiments, the second reactantexposure phase may also include igniting a plasma (not shown in theFigures). In some embodiments the thin layer of film may be depositedwithout use of a plasma. In some embodiments, the chamber is optionallypurged after the second reactant exposure phase during the purge phase.The purge phase may be performed to remove byproducts or excess secondreactant in gas phase from the chamber. In some embodiments, the chamberis not purged.

Operations 404 and 406 of FIG. 4 may be optionally repeated one or moretimes. Performing operations 404 and 406 may constitute an ALD cycle asdescribed above with respect to FIG. 1A. In various embodiments,operations 400-406 are repeated one or more times. A combination ofrepeated cycles of operations 400 and 402, and repeated cycles ofoperations 404 and 406 may be performed in further cycles. For example,in some embodiments, a cycle may include performing operations 400-402twice, and/or performing operations 404-406 three times, and may also berepeated two or more times. In some embodiments, cycles of operations400-402 and operations 404-406 are performed sequentially. For example,after performing operations 400-402, operations 404-406 are performed,and/or vice versa. The frequency of cycles and the number of cycles usedin a process may depend on the type of application disclosed embodimentsare used for.

Referring to FIG. 5, a plot of film thickness evaluated againstprogressive alternating deposition, such as ALD completed in operation204 a of FIG. 2, and etch procedures, such as ALE completed in operation210 of FIG. 2, is shown. Specifically, in some embodiments, aluminumnitride (AlN) may be deposited on either a dielectric, such as silicondioxide (SiO₂), and/or a metal, such as copper (Cu), via ALD.Alternatively, in some embodiments, AlN, or other materials such as SiO₂and/or Cu may be deposited on a substrate made of substantially aluminumnitride (AlN).

As shown in FIG. 5, deposition of AlN on either a substrate comprisingSiO₂ or Cu results in, for example, distinct AlN film thickness growthpatterns relative to the substrate upon which AlN is deposited, namelySiO₂ or Cu. The relative thickness of deposited materials and/or film,i.e. “film thickness,” may progress substantially as shown, with rapidgrowth observed for AlN as deposited on a SiO₂ substrate. In contrast,film thickness growth of AlN deposited on a Cu substrate may, forexample, remain stagnant for an initial period of time due to nucleationdelays associated with such a deposition. A subsequent etch operationthen reduces the film thickness the AlN deposited on either the SiO₂substrate and/or the Cu substrate, with AlN film deposited on the Cusubstrate returning and/or being reset to an initial zero thicknesscondition. Such deposition and etch operations and/or cycles may berepeated as desired to accomplish certain desirable film thicknesses ofAlN on, for example, a SiO₂ substrate and/or Cu substrate, as discussed.

Apparatus

FIG. 7 depicts a schematic illustration of an embodiment of an atomiclayer deposition (ALD) process station 700 having a process chamber body702 for maintaining a low pressure environment, suitable for conductingselective deposition as described herein. A plurality of ALD processstations 700 may be included in a common low pressure process toolenvironment. For example, FIG. 8 depicts an embodiment of amulti-station processing tool 800. In some embodiments, one or morehardware parameters of ALD process station 700 including those discussedin detail below may be adjusted programmatically by one or more computercontrollers 750.

ALD process station 700 fluidly communicates with reactant deliverysystem 701 a for delivering process gases to a distribution showerhead706. Reactant delivery system 701 a includes a mixing vessel 704 forblending and/or conditioning process gases, such as an aminosilaneprecursor gas, or oxidizing agent gas (e.g., ozone), or ammonia and/ornitrogen gas, for delivery to showerhead 706. One or more mixing vesselinlet valves 720 may control introduction of process gases to mixingvessel 704. Nitrogen plasma and/or ammonia plasma may also be deliveredto the showerhead 706 or may be generated in the ALD process station700.

As an example, the embodiment of FIG. 7 includes a vaporization point703 for vaporizing liquid reactant to be supplied to the mixing vessel704. In some embodiments, vaporization point 703 may be a heatedvaporizer. The saturated reactant vapor produced from such vaporizersmay condense in downstream delivery piping. Exposure of incompatiblegases to the condensed reactant may create small particles. These smallparticles may clog piping, impede valve operation, contaminatesubstrates, etc. Some approaches to addressing these issues involvepurging and/or evacuating the delivery piping to remove residualreactant. However, purging the delivery piping may increase processstation cycle time, degrading process station throughput. Thus, in someembodiments, delivery piping downstream of vaporization point 703 may beheat traced. In some examples, mixing vessel 704 may also be heattraced. In one non limiting example, piping downstream of vaporizationpoint 703 has an increasing temperature profile extending fromapproximately 100° C. to approximately 150° C. at a mixing vessel 704.

In some embodiments, liquid precursor or liquid reactant may bevaporized at a liquid injector. For example, a liquid injector mayinject pulses of a liquid reactant into a carrier gas stream upstream ofthe mixing vessel. In one embodiment, a liquid injector may vaporize thereactant by flashing the liquid from a higher pressure to a lowerpressure. In another example, a liquid injector may atomize the liquidinto dispersed microdroplets that are subsequently vaporized in a heateddelivery pipe. Smaller droplets may vaporize faster than largerdroplets, reducing a delay between liquid injection and completevaporization. Faster vaporization may reduce a length of pipingdownstream from vaporization point 703. In one scenario, a liquidinjector may be mounted directly to mixing vessel 704. In anotherscenario, a liquid injector may be mounted directly to showerhead 706.

In some embodiments, a liquid flow controller (LFC) upstream ofvaporization point 703 may be provided for controlling a mass flow ofliquid for vaporization and delivery to process station 700. Forexample, the LFC may include a thermal mass flow meter (MFM) locateddownstream of the LFC. A plunger valve of the LFC may then be adjustedresponsive to feedback control signals provided by aproportional-integral-derivative (PID) controller in electricalcommunication with the MFM. However, it may take one second or more tostabilize liquid flow using feedback control. This may extend a time fordosing a liquid reactant. Thus, in some embodiments, the LFC may bedynamically switched between a feedback control mode and a directcontrol mode. In some embodiments, this may be performed by disabling asense tube of the LFC and the PID controller.

Showerhead 706 distributes process gases toward substrate 712. In theembodiment shown in FIG. 7, the substrate 712 is located beneathshowerhead 706 and is shown resting on a pedestal 708. Showerhead 706may have any suitable shape, and may have any suitable number andarrangement of ports for distributing process gases to substrate 712.

In some embodiments, pedestal 708 may be raised or lowered to exposesubstrate 712 to a volume between the substrate 712 and the showerhead706. It will be appreciated that, in some embodiments, pedestal heightmay be adjusted programmatically by a suitable computer controller 750.

In another scenario, adjusting a height of pedestal 708 may allow aplasma density to be varied during plasma activation cycles in theprocess in embodiments where a plasma is ignited. At the conclusion ofthe process phase, pedestal 708 may be lowered during another substratetransfer phase to allow removal of substrate 712 from pedestal 708.

In some embodiments, pedestal 708 may be temperature controlled viaheater 710. In some embodiments, the pedestal 708 may be heated to atemperature of at least about 250° C., or in some embodiments, less thanabout 300° C., such as about 250° C., during deposition of siliconnitride films as described in disclosed embodiments. In someembodiments, the pedestal is set at a temperature between about 50° C.and about 300° C., such as at a temperature between about 200° C. andabout 275° C. In some embodiments, the pedestal is set at a temperaturebetween about 50° C. and about 300° C. In some embodiments, the pedestalis set at a temperature between about 200° C. and about 275° C.

Further, in some embodiments, pressure control for process station 700may be provided by butterfly valve 718. As shown in the embodiment ofFIG. 7, butterfly valve 718 throttles a vacuum provided by a downstreamvacuum pump (not shown in the Figures). However, in some embodiments,pressure control of process station 700 may also be adjusted by varyinga flow rate of one or more gases introduced to the process station 700.

In some embodiments, a position of showerhead 706 may be adjustedrelative to pedestal 708 to vary a volume between the substrate 712 andthe showerhead 706. Further, it will be appreciated that a verticalposition of pedestal 708 and/or showerhead 706 may be varied by anysuitable mechanism within the scope of the present disclosure. In someembodiments, pedestal 708 may include a rotational axis for rotating anorientation of substrate 712. It will be appreciated that, in someembodiments, one or more of these example adjustments may be performedprogrammatically by one or more suitable computer controllers 750.

In some embodiments where plasma may be used as discussed above,showerhead 706 and pedestal 708 electrically communicate with a radiofrequency (RF) power supply 714 and matching network 716 for powering aplasma. In some embodiments, the plasma energy may be controlled bycontrolling one or more of a process station pressure, a gasconcentration, an RF source power, an RF source frequency, and a plasmapower pulse timing. For example, RF power supply 714 and matchingnetwork 716 may be operated at any suitable power to form a plasmahaving a desired composition of radical species. Examples of suitablepowers are about 150 W to about 6000 W. Plasma may be used duringtreatment of a silicon nitride surface prior to selective deposition ofsilicon oxide on silicon oxide relative to silicon nitride. RF powersupply 714 may provide RF power of any suitable frequency. In someembodiments, RF power supply 714 may be configured to control high- andlow-frequency RF power sources independently of one another. Example lowfrequency RF frequencies may include, but are not limited to,frequencies between 0 kHz and 500 kHz. Example high-frequency RFfrequencies may include, but are not limited to, frequencies between 1.8MHz and 2.45 GHz, or greater than about 13.56 MHz, or greater than 27MHz, or greater than 40 MHz, or greater than 60 MHz. It will beappreciated that any suitable parameters may be modulated discretely orcontinuously to provide plasma energy for the surface reactions.

In some embodiments, the plasma may be monitored in-situ by one or moreplasma monitors. In one scenario, plasma power may be monitored by oneor more voltage, current sensors (e.g., VI probes). In another scenario,plasma density and/or process gas concentration may be measured by oneor more optical emission spectroscopy sensors (OES). In someembodiments, one or more plasma parameters may be programmaticallyadjusted based on measurements from such in-situ plasma monitors. Forexample, an OES sensor may be used in a feedback loop for providingprogrammatic control of plasma power. It will be appreciated that, insome embodiments, other monitors may be used to monitor the plasma andother process characteristics. Such monitors may include, but are notlimited to, infrared (IR) monitors, acoustic monitors, and pressuretransducers.

In some embodiments, instructions for a controller 750 may be providedvia input/output control (IOC) sequencing instructions. In one example,the instructions for setting conditions for a process phase may beincluded in a corresponding recipe phase of a process recipe. In somecases, process recipe phases may be sequentially arranged, so that allinstructions for a process phase are executed concurrently with thatprocess phase. In some embodiments, instructions for setting one or morereactor parameters may be included in a recipe phase. For example, afirst recipe phase may include instructions for setting a flow rate ofan inert and/or an ammonia and/or nitrogen reactant gas, instructionsfor setting a flow rate of a carrier gas (such as argon), instructionsfor igniting a plasma, and time delay instructions for the first recipephase. A second recipe phase may include instructions for setting a flowrate of an inert and/or aminosilane silicon precursor gas, instructionsfor setting a flow rate of a carrier gas (such as argon), and time delayinstructions for a second recipe phase. A third, subsequent recipe phasemay include instructions for modulating or stopping a flow rate of aninert and/or a reactant gas, and instructions for modulating a flow rateof a carrier or purge gas and time delay instructions for the thirdrecipe phase. A fourth recipe phase may include instructions formodulating a flow rate of an oxidizing agent gas such as ozone,instructions for modulating the flow rate of a carrier or purge gas, andtime delay instructions for the fourth recipe phase. A fifth, subsequentrecipe phase may include instructions for modulating or stopping a flowrate of an inert and/or a reactant gas, and instructions for modulatinga flow rate of a carrier or purge gas and time delay instructions forthe fifth recipe phase. It will be appreciated that these recipe phasesmay be further subdivided and/or iterated in any suitable way within thescope of the disclosed embodiments. In some embodiments, the controller750 may include any of the features described below with respect tosystem controller 850 of FIG. 8.

As described above, one or more process stations may be included in amulti-station processing tool 800 as shown in FIG. 8. The multi-stationprocessing tool may, in some embodiments, be from the VECTOR® family oftools and/or products available from Lam Research of Fremont, Calif.,and conduct or otherwise assist with, ALD as presented and described inconnection with FIGS. 1-3. FIG. 8 shows a schematic view of anembodiment of a multi-station processing tool 800 with an inbound loadlock 802 and an outbound load lock 804, either or both of which mayinclude a remote plasma source. A robot 806 at atmospheric pressure isconfigured to move wafers from a cassette loaded through a pod 808 intoinbound load lock 802 via an atmospheric port 810. A wafer is placed bythe robot 806 on a pedestal 812 in the inbound load lock 802, theatmospheric port 810 is closed, and the load lock is pumped down. Wherethe inbound load lock 802 includes a remote plasma source, the wafer maybe exposed to a remote plasma treatment to treat the silicon nitridesurface in the load lock prior to being introduced into a processingchamber 814. Further, the wafer also may be heated in the inbound loadlock 802 as well, for example, to remove moisture and adsorbed gases.Next, a chamber transport port 816 to processing chamber 814 is opened,and another robot (not shown) places the wafer into the reactor on apedestal of a first station shown in the reactor for processing. Whilethe embodiment depicted in FIG. 8 includes load locks, it will beappreciated that, in some embodiments, direct entry of a wafer into aprocess station may be provided.

The depicted processing chamber 814 includes four process stations,numbered from 1 to 4 in the embodiment shown in FIG. 8. Each station hasa heated pedestal (shown at 818 for station 1), and gas line inlets. Itwill be appreciated that in some embodiments, each process station mayhave different or multiple purposes. For example, in some embodiments, aprocess station may be switchable between an ALD and plasma-enhanced ALDprocess mode. Additionally or alternatively, in some embodiments,processing chamber 814 may include one or more matched pairs of ALD andplasma-enhanced ALD process stations. While the depicted processingchamber 814 includes four stations, it will be understood that aprocessing chamber according to the present disclosure may have anysuitable number of stations. For example, in some embodiments, aprocessing chamber may have five or more stations, while in otherembodiments a processing chamber may have three or fewer stations.

In some embodiments, that shown in FIG. 8 may interact and/or otherwiseengage with a wafer handling system for transferring wafers withinprocessing chamber 814. In some embodiments, the wafer handling systemmay transfer wafers between various process stations and/or between aprocess station and a load lock. It will be appreciated that anysuitable wafer handling system may be employed. Non-limiting examplesinclude wafer carousels and wafer handling robots. FIG. 8 also depictsan embodiment of a system controller 850 employed to control processconditions and hardware states of process tool 800. System controller850 may include one or more memory devices 856, one or more mass storagedevices 854, and one or more processors 852. Processor 852 may include aCPU or computer, analog, and/or digital input/output connections,stepper motor controller boards, etc.

In some embodiments, system controller 850 controls all of theactivities of process tool 800. System controller 850 executes systemcontrol software 858 stored in mass storage device 854, loaded intomemory device 856, and executed on processor 852. Alternatively, thecontrol logic may be hard coded in the controller 850. ApplicationsSpecific Integrated Circuits, Programmable Logic Devices (e.g.,field-programmable gate arrays, or FPGAs) and the like may be used forthese purposes. In the following discussion, wherever “software” or“code” is used, functionally comparable hard coded logic may be used inits place. System control software 858 may include instructions forcontrolling the timing, mixture of gases, gas flow rates, chamber and/orstation pressure, chamber and/or station temperature, wafer temperature,target power levels, RF power levels, substrate pedestal, chuck and/orsusceptor position, and other parameters of a particular processperformed by process tool 800. System control software 858 may beconfigured in any suitable way. For example, various process toolcomponent subroutines or control objects may be written to controloperation of the process tool components used to carry out variousprocess tool processes. System control software 858 may be coded in anysuitable computer readable programming language.

In some embodiments, system control software 858 may includeinput/output control (IOC) sequencing instructions for controlling thevarious parameters described above. Other computer software and/orprograms stored on mass storage device 854 and/or memory device 856associated with system controller 850 may be employed in someembodiments. Examples of programs or sections of programs for thispurpose include a substrate positioning program, a process gas controlprogram, a pressure control program, a heater control program, and aplasma control program.

A substrate positioning program may include program code for processtool components that are used to load the substrate onto pedestal 818and to control the spacing between the substrate and other parts ofprocess tool 800.

A process gas control program may include code for controlling gascomposition (e.g., aminosilane gases, and oxidizing agent gases,ammonia, nitrogen, carrier gases and/or purge gases as described herein)and flow rates and optionally for flowing gas into one or more processstations prior to deposition in order to stabilize the pressure in theprocess station. A pressure control program may include code forcontrolling the pressure in the process station by regulating, forexample, a throttle valve in the exhaust system of the process station,a gas flow into the process station, etc.

A heater control program may include code for controlling the current toa heating unit that is used to heat the substrate. Alternatively, theheater control program may control delivery of a heat transfer gas (suchas helium) to the substrate.

A plasma control program may include code for setting RF power levelsapplied to the process electrodes in one or more process stations inaccordance with the embodiments herein.

A pressure control program may include code for maintaining the pressurein the reaction chamber in accordance with the embodiments herein.

In some embodiments, there may be a user interface associated withsystem controller 850. The user interface may include a display screen,graphical software displays of the apparatus and/or process conditions,and user input devices such as pointing devices, keyboards, touchscreens, microphones, etc.

In some embodiments, parameters adjusted by system controller 850 mayrelate to process conditions. Non-limiting examples include process gascomposition and flow rates, temperature, pressure, plasma conditions(such as RF bias power levels), etc. These parameters may be provided tothe user in the form of a recipe, which may be entered utilizing theuser interface.

Signals for monitoring the process may be provided by analog and/ordigital input connections of system controller 850 from various processtool sensors. The signals for controlling the process may be output onthe analog and digital output connections of process tool 800.Non-limiting examples of process tool sensors that may be monitoredinclude mass flow controllers, pressure sensors (such as manometers),thermocouples, etc. Appropriately programmed feedback and controlalgorithms may be used with data from these sensors to maintain processconditions.

System controller 850 may provide program instructions for implementingthe above-described deposition processes. The program instructions maycontrol a variety of process parameters, such as DC power level, RF biaspower level, pressure, temperature, etc. The instructions may controlthe parameters to operate in-situ deposition of film stacks according tovarious embodiments described herein.

The system controller 850 will typically include one or more memorydevices and one or more processors configured to execute theinstructions so that the apparatus will perform a method in accordancewith disclosed embodiments. Machine-readable media containinginstructions for controlling process operations in accordance withdisclosed embodiments may be coupled to the system controller 850.

In some implementations, the system controller 850 is part of a system,which may be part of the above-described examples. Such systems caninclude semiconductor processing equipment, including a processing toolor tools, chamber or chambers, a platform or platforms for processing,and/or specific processing components (a wafer pedestal, a gas flowsystem, etc.). These systems may be integrated with electronics forcontrolling their operation before, during, and after processing of asemiconductor wafer or substrate. The electronics may be referred to asthe “controller,” which may control various components or subparts ofthe system or systems. The system controller 850, depending on theprocessing conditions and/or the type of system, may be programmed tocontrol any of the processes disclosed herein, including the delivery ofprocessing gases, temperature settings (e.g., heating and/or cooling),pressure settings, vacuum settings, power settings, radio frequency (RF)generator settings, RF matching circuit settings, frequency settings,flow rate settings, fluid delivery settings, positional and operationsettings, wafer transfers into and out of a tool and other transfertools and/or load locks connected to or interfaced with a specificsystem.

Broadly speaking, the system controller 850 may be defined aselectronics having various integrated circuits, logic, memory, and/orsoftware that receive instructions, issue instructions, controloperation, enable cleaning operations, enable endpoint measurements, andthe like. The integrated circuits may include chips in the form offirmware that store program instructions, digital signal processors(DSPs), chips defined as application specific integrated circuits(ASICs), and/or one or more microprocessors, or microcontrollers thatexecute program instructions (e.g., software). Program instructions maybe instructions communicated to the system controller 850 in the form ofvarious individual settings (or program files), defining operationalparameters for carrying out a particular process on or for asemiconductor wafer or to a system. The operational parameters may, insome embodiments, be part of a recipe defined by process engineers toaccomplish one or more processing steps during the fabrication of one ormore layers, materials, metals, oxides, silicon, silicon dioxide,surfaces, circuits, and/or dies of a wafer.

The system controller 850, in some implementations, may be a part of orcoupled to a computer that is integrated with, coupled to the system,otherwise networked to the system, or a combination thereof. Forexample, the system controller 850 may be in the “cloud” or all or apart of a fab host computer system, which can allow for remote access ofthe wafer processing. The computer may enable remote access to thesystem to monitor current progress of fabrication operations, examine ahistory of past fabrication operations, examine trends or performancemetrics from a plurality of fabrication operations, to change parametersof current processing, to set processing steps to follow a currentprocessing, or to start a new process. In some examples, a remotecomputer (e.g. a server) can provide process recipes to a system over anetwork, which may include a local network or the Internet. The remotecomputer may include a user interface that enables entry or programmingof parameters and/or settings, which are then communicated to the systemfrom the remote computer. In some examples, the system controller 850receives instructions in the form of data, which specify parameters foreach of the processing steps to be performed during one or moreoperations. It should be understood that the parameters may be specificto the type of process to be performed and the type of tool that thesystem controller 850 is configured to interface with or control. Thusas described above, the system controller 850 may be distributed, suchas by including one or more discrete controllers that are networkedtogether and working towards a common purpose, such as the processes andcontrols described herein. An example of a distributed controller forsuch purposes would be one or more integrated circuits on a chamber incommunication with one or more integrated circuits located remotely(such as at the platform level or as part of a remote computer) thatcombine to control a process on the chamber.

Without limitation, example systems may include a plasma etch chamber ormodule, a deposition chamber or module, a spin-rinse chamber or module,a metal plating chamber or module, a clean chamber or module, a beveledge etch chamber or module, a physical vapor deposition (PVD) chamberor module, a chemical vapor deposition (CVD) chamber or module, an ALDchamber or module, an atomic layer etch (ALE) chamber or module, an ionimplantation chamber or module, a track chamber or module, and any othersemiconductor processing systems that may be associated or used in thefabrication and/or manufacturing of semiconductor wafers.

As noted above, depending on the process step or steps to be performedby the tool, the system controller 850 might communicate with one ormore of other tool circuits or modules, other tool components, clustertools, other tool interfaces, adjacent tools, neighboring tools, toolslocated throughout a factory, a main computer, another controller, ortools used in material transport that bring containers of wafers to andfrom tool locations and/or load ports in a semiconductor manufacturingfactory.

An appropriate apparatus for performing the methods disclosed herein isfurther discussed and described in U.S. patent application Ser. No.13/084,399 (now U.S. Pat. No. 8,728,956), filed Apr. 11, 2011, andtitled “PLASMA ACTIVATED CONFORMAL FILM DEPOSITION”; and Ser. No.13/084,305, filed Apr. 11, 2011, and titled “SILICON NITRIDE FILMS ANDMETHODS,” each of which is incorporated herein in its entireties.

The apparatus/process described herein may be used in conjunction withlithographic patterning tools or processes, for example, for thefabrication or manufacture of semiconductor devices, displays, LEDs,photovoltaic panels and the like. Typically, though not necessarily,such tools/processes will be used or conducted together in a commonfabrication facility. Lithographic patterning of a film typicallyincludes some or all of the following operations, each operation enabledwith a number of possible tools: (1) application of photoresist on aworkpiece, i.e., substrate, using a spin-on or spray-on tool; (2) curingof photoresist using a hot plate or furnace or UV curing tool; (3)exposing the photoresist to visible or UV or x-ray light with a toolsuch as a wafer stepper; (4) developing the resist so as to selectivelyremove resist and thereby pattern it using a tool such as a wet bench;(5) transferring the resist pattern into an underlying film or workpieceby using a dry or plasma-assisted etching tool; and (6) removing theresist using a tool such as an RF or microwave plasma resist stripper.

Referring generally to FIG. 9, inductively coupled plasma (ICP) reactorswhich, in certain embodiments, may be suitable for atomic layer etching(ALE) operations and/or atomic layer deposition (ALD) operations are nowdescribed. Such ICP reactors have also been described in U.S. PatentApplication Publication No. 2014/0170853, filed Dec. 10, 2013, andtitled “IMAGE REVERSAL WITH AHM GAP FILL FOR MULTIPLE PATTERNING,”hereby incorporated by reference in its entirety and for all purposes.Although ICP reactors are described herein, in some embodiments, itshould be understood that capacitively coupled plasma (CCP) reactors mayalso be used.

FIG. 9 schematically shows a cross-sectional view of an inductivelycoupled plasma integrated etching and deposition apparatus 900appropriate for implementing certain embodiments herein, an example ofwhich is a Kiyo™ reactor, produced by Lam Research Corp. of Fremont,Calif. In some embodiments, ALE as presented and described in connectionwith FIGS. 1-4, may be primarily conducted on the Kiyo™ reactor. Theinductively coupled plasma apparatus 900 includes an overall processchamber structurally defined by chamber walls 901 and a window 911extending lengthwise there between. The chamber walls 901 may befabricated from stainless steel or aluminum. The window 911 may befabricated from quartz or other dielectric material. An optionalinternal plasma grid 950 divides the overall processing chamber into anupper sub-chamber 902 and a lower sub-chamber 903 positioned beneaththereof. Further, in some embodiments, the plasma grid 950 may beremoved, thereby creating and/or utilizing a chamber space made of bothsub-chambers 902 and 903. A chuck 917 is positioned within the lowersub-chamber 903 near the bottom inner surface. The chuck 917 isconfigured to receive and hold a semiconductor wafer 919 upon which theetching and deposition processes are performed. The chuck 917 can be anelectrostatic chuck for supporting the wafer 919 when present. In someembodiments, an edge ring (not shown) surrounds the chuck 917, and hasan upper surface that is approximately planar with a top surface of awafer 919, when present over the chuck 917. In some embodiments, thechuck 917 also includes electrostatic electrodes for chucking anddechucking the wafer. A filter and DC clamp power supply (not shown inthe Figures) may be provided for this purpose. Other control systems forlifting the wafer 919 off the chuck 917 can also be provided. The chuck917 can be electrically charged using an RF power supply 923. The RFpower supply 923 is connected to matching circuitry 821 through aconnection 927. The matching circuitry 921 is connected to the chuck 917through a connection 925. In this manner, the RF power supply 923 isconnected to the chuck 917.

Elements for plasma generation include a coil 933 is positioned abovewindow 911. In some embodiments, a coil is not used in disclosedembodiments. The coil 933 is fabricated from an electrically conductivematerial and includes at least one complete turn. The example of a coil933 shown in FIG. 9 includes three turns. The cross-sections of coil 933are shown with symbols, and coils having an “X” extend rotationally intothe page, while coils having a “●” extend rotationally out of the page.Elements for plasma generation also include an RF power supply 941configured to supply RF power to the coil 933. In general, the RF powersupply 941 is connected to matching circuitry 939 through a connection945. The matching circuitry 939 is connected to the coil 933 through aconnection 943. In this manner, the RF power supply 941 is connected tothe coil 933. An optional Faraday shield 949 is positioned between thecoil 933 and the window 911. The Faraday shield 949 is maintained in aspaced apart relationship relative to the coil 933. The Faraday shield949 is disposed immediately above the window 911. The coil 933, theFaraday shield 949, and the window 911 are each configured to besubstantially parallel to one another in, for example, the configurationshown in FIG. 9. The Faraday shield may prevent metal or other speciesfrom depositing on the dielectric window of the plasma chamber.

Process gases (e.g., chlorine, argon, silicon tetrachloride, oxygen,nitrogen, etc.) may be flowed into the processing chamber through one ormore main gas flow inlets 960 positioned in the upper chamber and/orthrough one or more side gas flow inlets 970. Likewise, though notexplicitly shown, similar gas flow inlets may be used to supply processgases to a capacitively coupled plasma (CCP) processing chamber. Avacuum pump, e.g., a one or two stage mechanical dry pump and/orturbomolecular pump 940, may be used to draw process gases out of theprocess chamber and to maintain a pressure within the process chamber900. For example, the pump may be used to evacuate the chamber during apurge operation of ALD. A valve-controlled conduit may be used tofluidically connect the vacuum pump to the processing chamber so as toselectively control application of the vacuum environment provided bythe vacuum pump. This may be done employing a closed-loop-controlledflow restriction device, such as a throttle valve (not shown in FIG. 9)or a pendulum valve (not shown in FIG. 9), during operational plasmaprocessing. Likewise, a vacuum pump and/or a valve controlled fluidicconnection to the capacitively coupled plasma (CCP) processing chambermay also be used.

During operation of the ICP apparatus 900, one or more process gases maybe supplied through the gas flow inlets 960 and/or 970. In certainembodiments, process gas may be supplied only through the main gas flowinlet 960, or only through the side gas flow inlet 970. In some cases,the gas flow inlets shown in the figure may be replaced by more complexgas flow inlets and/or one or more showerheads, for example. The Faradayshield 949 and/or optional grid 950 may include internal channels andholes that allow delivery of process gases to the chamber. Either orboth of Faraday shield 949 and optional grid 950 may serve as ashowerhead for delivery of process gases. In some embodiments, a liquidvaporization and delivery system may be situated upstream of thechamber, such that once a liquid reactant or precursor is vaporized, thevaporized reactant or precursor is introduced into the chamber via a gasflow inlet 960 and/or 970. Example liquid precursors include SiCl₄ andsilicon amides.

Radio frequency power is supplied from the RF power supply 941 to thecoil 933 to cause an RF current to flow into and/or through the coil933. The RF current flowing through the coil 933 generates anelectromagnetic field about the coil 933, which generates an inductivecurrent within the upper sub-chamber 902. The physical and chemicalinteractions of various generated ions and radicals with the wafer 919selectively etch features of and deposit layers on the wafer, such asthat discussed and described for the ALE and/or ALD processes shown inFIG. 1A, for example.

If the plasma grid is used such that there is both an upper sub-chamber902 and a lower sub-chamber 903, the inductive current acts on gaspresent in the upper sub-chamber 902 to generate an electron-ion plasmain the upper sub-chamber 902. The optional internal plasma grid 950limits the amount of hot electrons in the lower sub-chamber 903. In someembodiments, the apparatus is designed and operated such that the plasmapresent in the lower sub-chamber 903 is an “ion-ion” plasma.

Both the upper electron-ion plasma and the lower ion-ion plasma maycontain positive and negative ions, though the ion-ion plasma will havea greater ratio of negative ions to positive ions. Volatile etchingand/or deposition byproducts may be removed from the lower-sub-chamber903 through port 922. The chuck 917 disclosed herein may operate atelevated temperatures ranging between about 10° C. and about 250° C. Thetemperature will depend on the process operation and specific recipe.

The chamber may be coupled to facilities (not shown in FIG. 9) wheninstalled in a clean room or a fabrication facility. Such facilities mayinclude plumbing that provides processing gases, vacuum, temperaturecontrol, and/or environmental particle control. These facilities arecoupled to the chamber, when installed in the target fabricationfacility. Additionally, the chamber may be coupled to a transfer chamberthat allows robotics to transfer semiconductor wafers into and out ofthe chamber using, for example, typical automation.

In some embodiments, a system controller 930 (which may include one ormore physical or logical controllers) controls some or all of theoperations of a processing chamber. The system controller 930 mayinclude one or more memory devices and one or more processors. In someembodiments, the apparatus includes a switching system for controllingflow rates and durations when disclosed embodiments are performed. Insome embodiments, the apparatus may have a switching time of up to about500 ms, or up to about 750 ms. Switching time may depend on the flowchemistry, recipe chosen, reactor architecture, and various otherfactors, for example.

In some implementations, a system controller, or controller 930 is partof a system, which may be part of and/or otherwise integrated with theabove-described examples. Such systems can comprise semiconductorprocessing equipment, including a processing tool or tools, chamber orchambers, a platform or platforms for processing, and/or specificprocessing components (a wafer pedestal, a gas flow system, etc.). Thesesystems may be integrated with electronics for controlling theiroperation before, during, and after processing of a semiconductor waferor substrate. The electronics may be referred to collectively as the“controller,” which may control various components or subparts of thesystem or systems. The controller 930, depending on the processingparameters and/or the type of system, may be programmed to control anyof the processes disclosed herein, including the delivery of processinggases, temperature settings (e.g., heating and/or cooling), pressuresettings, vacuum settings, power settings, radio frequency (RF)generator settings, RF matching circuit settings, frequency settings,flow rate settings, fluid delivery settings, positional and operationsettings, wafer transfers into and out of a tool and other transfertools and/or load locks connected to or interfaced with a specificsystem.

Broadly speaking, the controller 930 may be defined as electronicshaving various integrated circuits, logic, memory, and/or software thatreceive instructions, issue instructions, control operation, enablecleaning operations, enable endpoint measurements, and the like. Theintegrated circuits may include chips in the form of firmware that storeprogram instructions, digital signal processors (DSPs), chips defined asapplication specific integrated circuits (ASICs), and/or one or moremicroprocessors, or microcontrollers that execute program instructions(e.g., software). Program instructions may be instructions communicatedto the controller in the form of various individual settings (or programfiles), defining operational parameters for carrying out a particularprocess on or for a semiconductor wafer or to a system. The operationalparameters may, in some embodiments, be part of a recipe defined byprocess engineers to accomplish one or more processing steps during thefabrication of one or more layers, materials, metals, oxides, silicon,silicon dioxide (SiO₂), surfaces, circuits, and/or dies of a wafer.

The controller 930, in some implementations, may be a part of or coupledto a computer that is integrated with, coupled to the system, otherwisenetworked to the system, or a combination thereof. For example, thecontroller may be in a “cloud” and/or “cloud”-type computer network orall or at least part of a fab host computer system, which can allow forremote access of the wafer processing. The computer may enable remoteaccess to the system to monitor current progress of fabricationoperations, examine a history of past fabrication operations, examinetrends or performance metrics from a plurality of fabricationoperations, to change parameters of current processing, to setprocessing steps to follow a current processing, or to start a newprocess. In some examples, a remote computer (e.g., a server) canprovide process recipes to a system over a network, which may include alocal network or the Internet. The remote computer may include a userinterface that enables entry or programming of parameters and/orsettings, which are then communicated to the system from the remotecomputer. In some examples, the controller 930 receives instructions inthe form of data, which specify parameters for each of the processingsteps to be performed during one or more operations. It should beunderstood that the parameters may be specific to the type of process tobe performed and the type of tool that the controller is configured tointerface with or control. Thus as described above, the controller 930may be distributed, such as by comprising one or more discretecontrollers that are networked together and working towards a commonpurpose, such as the processes and controls described herein. An exampleof a distributed controller for such purposes would be one or moreintegrated circuits on a chamber in communication with one or moreintegrated circuits located remotely (such as at the platform level oras part of a remote computer) that combine to control a process on thechamber.

Without limitation, example systems may include a plasma etch chamber ormodule, a deposition chamber or module, a spin-rinse chamber or module,a metal plating chamber or module, a clean chamber or module, a beveledge etch chamber or module, a physical vapor deposition (PVD) chamberor module, a chemical vapor deposition (CVD) chamber or module, an ALDchamber or module, an ALE chamber or module, an ion implantation chamberor module, a track chamber or module, and any other semiconductorprocessing systems that may be associated or used in the fabricationand/or manufacturing of semiconductor wafers.

As noted above, depending on the process step or steps to be performedby the tool, the controller might communicate with one or more of othertool circuits or modules, other tool components, cluster tools, othertool interfaces, adjacent tools, neighboring tools, tools locatedthroughout a factory, a main computer, another controller, or tools usedin material transport that bring containers of wafers to and from toollocations and/or load ports in a semiconductor manufacturing factory.

FIG. 10 depicts a semiconductor process cluster architecture withvarious modules that interface with a vacuum transfer module 1038 (VTM).The arrangement of transfer modules to “transfer” wafers among multiplestorage facilities and processing modules may be referred to as a“cluster tool architecture” system. Airlock 1030, also known as a“loadlock” or transfer module, is shown in VTM 1038 with four processingmodules 1020 a-1020 d, which may be individual optimized to performvarious fabrication processes. By way of example, processing modules1020 a-1020 d may be implemented to perform substrate etching,deposition, ion implantation, wafer cleaning, sputtering, and/or othersemiconductor-related processes. In some embodiments, ALD and ALE areperformed in the same module. In some embodiments, ALD and ALE areperformed in different modules of the same tool. One or more of thesubstrate etching processing modules (any of 1020 a-1020 d) may beimplemented as disclosed herein, i.e., for depositing conformal films,selectively depositing films by ALD, etching patterns, and othersuitable functions in accordance with the disclosed embodiments. Airlock1030 and process module 1020 may be referred to as “stations.” Eachstation has a facet 1036 that interfaces the station to VTM 1038. Insideeach facet, sensors 1-18 are used to detect the passing of wafer 1026when moved between respective stations.

Robot 1022 transfers wafer 1026 between stations. In one embodiment,robot 1022 has one arm, and in another embodiment, robot 1022 has twoarms, where each arm has an end effector 1024 to pick wafers such aswafer 1026 for transport. Front-end robot 1032, in atmospheric transfermodule (ATM) 1040, is used to transfer wafers 1026 from cassette orFront Opening Unified Pod (FOUP) 1034 in Load Port Module (LPM) 1042 toairlock 1030. Module center 1028 inside process module 1020 a and/or1020 b is a suitable location for placing wafer 1026. Aligner 1044 inATM 1040 is used to align wafers.

In an exemplary processing method, a wafer is placed in one of the FOUPs1034 in the LPM 1042. Front-end robot 1032 transfers the wafer from theFOUP 1034 to the aligner 1044, which allows the wafer 1026 to beproperly centered before it is etched or processed. After being aligned,the wafer 1026 is moved by the front-end robot 1032 into an airlock1030. Because airlock modules have the ability to match the environmentbetween an ATM and a VTM, the wafer 1026 is able to move between the twopressure environments without being damaged. From the airlock module1030, the wafer 1026 is moved by robot 1022 through VTM 1038 into one ofthe process modules 1020 a-1020 d. Specifically, the robot 1022 uses endeffectors 1024 located on each of its arms, for example, to grasp thewafer 1026 to move it as described, i.e. through VTM 1038 into one ofthe process modules 1020 a-1020 d. Once the wafer 1026 has beenprocessed, it is moved by robot 1022 from the process modules 1020a-1020 d to an airlock module 1030. From here, the wafer 1026 may bemoved by the front-end robot 1032 to one of the FOUPs 1034 or to thealigner 1044.

It should be noted that the computer controlling the wafer movement canbe local to the cluster architecture, or can be located external to thecluster architecture in the manufacturing floor, or in a remote locationand connected to the cluster architecture via a network. Further, insome embodiments, a controller as described above with respect to FIGS.7-9 may be implemented with the tool in FIG. 10.

Further, in some embodiments, that shown and described in connectionwith FIGS. 1 and/or 2, namely selective deposition by ALD at operations104 and/or 204 a, and subsequent reset of the nucleation delaydifferential between different substrate materials by ALE at operations106 and/or 210, may be practiced and/or otherwise conducted in any oneor more of the apparatuses shown and discussed in FIGS. 7-10.

Preferentially, in some embodiments, ALD in operations 104 and/or 204 ais executed by a plasma-enhanced chemical vapor deposition (PECVD)product, such as those in the VECTOR® group of products available fromLam Research, Inc., of Fremont, Calif. Further, additional hybrid tooldeveloped by Lam Research may include both VECTOR® and Kiyo™ productsand/or tools on a common platform. Specifically, such a platform mayinclude configurations directed toward the completion of ALD procedureson VECTOR® products and ALE procedures on Kiyo™ products, where both theVECTOR® and Kiyo™ are operationally integrated in a common cluster. Sucha common cluster may allow for the ALD and/or ALE procedures describedherein to be completed without a vacuum break, or without breakingvacuum, thus presenting a useful alternative to traditional processcycling in and/or between vacuum deposition and/or etch chambers.

Further, any combination of one or more (or all) of the ALD and/or ALEprocedures shown and discussed in FIGS. 1-4 may be completed withoutotherwise comprising substrate surface integrity. Further, embodimentsinvolving the integration of VECTOR® and Kiyo™ products and/or tools mayresult in optimal throughout, rather than attempts to complete thediscussed ALD and/or ALE procedures on, for example, Kiyo™ productsalone. Moreover, in some embodiments, placement of VECTOR® and Kiyo™products and/or tools in the same cluster where ALD is performed onVECTOR® products and ALE is performed on Kiyo™ may eliminate orsubstantially reduce growth defects with reference to off-targetdeposition.

Additional integration of the described ALD and/or ALE procedures withother semiconductor-related processes is possible. Specifically, thatshown and described in connection with FIGS. 1-3 may be implemented withgap fill applications, patterning, selective layer growth of subsequentlayers from an initial layer, and/or selective protection of a layerduring etch, such as ALE, procedures.

CONCLUSION

Although the foregoing embodiments have been described in some detailfor purposes of clarity of understanding, it will be apparent thatcertain changes and modifications may be practiced within the scope ofthe appended claims. It should be noted that there are many alternativeways of implementing the processes, systems, and apparatus of thepresent embodiments. Accordingly, the present embodiments are to beconsidered as illustrative and not restrictive, and the embodiments arenot to be limited to the details given herein.

What is claimed is:
 1. An apparatus for processing substrates, theapparatus comprising: a process chamber having a substrate-supportingchuck; one or more gas inlets into the process chamber and associatedflow-control hardware; and a controller having a processor and a memory,wherein the processor and the memory are communicatively connected withone another, the processor is at least operatively connected with theflow-control hardware, and the memory stores computer-executableinstructions for controlling the processor to at least control theflow-control hardware by: (a) exposing a substrate housed in the processchamber to alternating pulses of a first reactant and a second reactantto deposit a film over the substrate, the substrate having a firstsubstrate material on which deposition of the film is intended and asecond substrate material on which deposition of the film is notintended, the second substrate material being different from the firstsubstrate material, and a nucleation delay for the first substratematerial being less than a nucleation delay for the second substratematerial according to a nucleation delay differential, which degradesupon proceeding with the film deposition; and (b) exposing the substratehoused in the chamber to alternating pulses of an etching gas and aremoval gas to etch a portion of the film deposited in (a) to reset thenucleation delay differential between the first and second substratematerials; wherein (a) and (b) result in net deposition of the film onthe first substrate material.
 2. The apparatus of claim 1, wherein thememory further stores computer-executable instructions for controllingthe processor to at least control the flow-control hardware by repeating(a) and (b) in the same chamber.
 3. The apparatus of claim 1, whereinthe memory further stores computer-executable instructions forcontrolling the processor to at least control the flow-control hardwareso that (a) and (b) are performed without breaking vacuum.
 4. Theapparatus of claim 2, wherein the memory further storescomputer-executable instructions for controlling the processor to atleast control the flow-control hardware so that (a) and (b) areperformed without breaking vacuum.
 5. The apparatus of claim 1, whereinthe memory further stores computer-executable instructions forcontrolling the processor to at least control the flow-control hardwareso that the first reactant is a deposition precursor to modify a surfaceof the substrate, and the second reactant is a reducing agent to depositthe material.
 6. The apparatus of claim 1, wherein the memory furtherstores computer-executable instructions for controlling the processor toat least control the flow-control hardware so that the material to bedeposited is aluminum nitride (AlN).
 7. The apparatus of claim 6,wherein the memory further stores computer-executable instructions forcontrolling the processor to at least control the flow-control hardwareso that trimethylaluminum provides aluminum for the aluminum nitride tobe deposited.
 8. The apparatus of claim 7, wherein the memory furtherstores computer-executable instructions for controlling the processor toat least control the flow-control hardware so that the trimethylaluminumis deposited in a temperature range from 250° C. to 350° C.
 9. Theapparatus of claim 1, wherein the memory further storescomputer-executable instructions for controlling the processor to atleast control the flow-control hardware so that the removal gas is acarrier gas selected from the group consisting of N₂, Ar, He, and Ne.